The present invention relates to aromatic diisocyanates containing N,N-disubstituted sulfonamide groups, to processes for their production and to a process for the production of polyurethane plastics from these diisocyanates.
Aromatic monoisocyanates of which the aromatic nuclei are substituted by N,N-dialkyl sulfonamide groups are known (see for example Swiss Pat. No. 411,449; Belgian Pat. No. 734,235; U.S. Pat. No. 3,576,872; Netherlands Published Application No. 7,105,350; and Japanese Laid Open Application No. 7,316,502). Such monoisocyanates are used as coupling reagents in color photography, as intermediate products for resins, polymers, dyes, bleaching agents, pharmaceutical products, disinfectants and insecticides.
However, aromatic diisocyanates containing N,N-disubstituted sulfonamide groups on the aromatic nucleus are unknown. French Pat. No. 1,465,165 describes a process for the production of aromatic amines from isocyanates by the acid-catalyzed thermolysis of the corresponding secondary or tertiary alkyl carbamic acid esters. This French Patent also mentions that N-alkyl sulfonamido-aryl (di)isocyanates might be used as starting materials for the production of these alkyl carbamic acid esters. However, these diisocyanates are not illustrated in any of the Examples. Further, the availability of any such material is questionable because if the corresponding N-alkyl sulfonamido-aryl (di)amines are phosgenated to produce the isocyanates, the N-alkyl sulfonamide group is in danger of reacting in the secondary reaction represented by the folllowing equation: ##STR2##